The toque macaque (Macaca sinica) is a reddish-brown-coloured Old World monkey endemic to Sri Lanka, where it is known as the rilewa or rilawa (Sinhala රිළවා), (hence "rillow" in the Oxford English Dictionary).
With age, the face of females turn slightly pink, prominent in the subsp. sinica.
M. s. aurifrons can be found sympatrically with subsp. sinica within intermediate regions of the country, such as Kegalle, parts of Kurunegala. They are also found in south-western parts of the island including Galle, and Matara districts, near to Kalu Ganga.
M. s. opisthomelas is recently identified as a separate subspecies. It can be found in the entire south-western region of central hill, (bordered with Ratnapura) and Nuwara Eliya districts. They can be seen around the Hakgala Botanical Garden and other cold climatic montane forest patches.
The three recognized subspecies of toque macaques are:
M. s. opisthomelas is similar to subsp. aurifrons, but has a long fur and contrasting golden color in the anterior part of its brown cap.
The three subspecies can be identified through the orientation of their different hair patterns.
The social status is highly structured in toque macaques, where there prevails dominance hierarchies among both males and females. A troop may consist of as few as 8 to as many as 40. When the troop becomes too large, social tension and aggression towards each other arise, causing some individuals to flee from the troop. This is noticeable in adults and sub adults, where a troop may consist largely of females. Newly appointed alpha males also show aggressiveness towards females, causing the females to flee. There are sightings of severe fights between individuals of the same troop and some get heavy wounds to cheeks, eyes, and sometimes broken arms.
When in estrous, the female's perineum becomes reddish in color and swells. This change is a signal to the males that she is ready to mate. There is an average of 18 month between births. After a 5–6 month gestation period, female macaque give birth to a single offspring. Offspring hold on to their mothers for about 2 months. During this time they learn survival techniques and social skills critical for survival. The infants are born into their social classes based on their mothers position in the troop. Young males are forced to abandon their troop when they are about 6–8 years of age. This prevents in-breeding and ensures that the current alpha male maintains his position in the troop. Leaving the troop is the only way a male can change his social standing. If he has good social skills and is strong he may become an alpha male. A single alpha male can father all of the troops' offspring.
Birth rarely occurs during the day or on the ground. During labor the female isolates herself from the group (about 100 m). The mother stands bipedally during parturition and assists the delivery with her hands. The infant is usually born 2 minutes after crowning. The infant can vocalize almost immediately after birth; it is important for the mother and infant to recognize each other's voices. Vocalization will be used to alert the mother of imminent danger, and can assist in finding each other if separated. After birth the mother licks the infant and orients it toward her breasts. She will resume foraging behavior within 20 minutes after parturition. The mother also eats part of the placenta, because it contains needed protein. The alpha female of the group asserts her power by taking part of the placenta for herself to eat.
They are fond of eating drooping yellow clusters of flowers of Cassia fistula. They eat any good thing making use of human detritus by going after plantains, pineapples, rice grains, papaws, and mangoes. Even there are plenty of foods present in natural habitation, toque macaques enjoy to take any food with little effort around human dwellings. They are occasionally seen around houses near a forest patch, where they invade all the fruiting plants in the day sessions and return to the forest cover in night. Because, these macaques have very little fear for humans and their companions-the dogs.
Cheek pouches enable toque macaques to store enough food while eating fast. In the dry zone, they are known to eat drupes of understory shrub Zizyphus, ripe fruits of Ficus, and Cordia species. They occasionally eat many small animals ranging from small insects to mammals like indian palm squirrels and Vandeleuria oleracea.
The lifespan of toque macaques in the wild is about the same as in captivity, up to 35 years. The expected lifespan in the wild is low due to high infant mortality rates. There is also significant mortality among adolescent males when they venture off to join a different troop. Once toque macaques have reached sexual maturity they will likely live to an old age. (Fooden, 1979; Michael and Crook, 1973).
IUCN listed toque macaque as vulnerable in their list due to habitat destruction and hunting, and also for taming for pets. All the three subspecies are recognized as vulnerable entirely in their natural habitats. With few patches of forests for survival, they engage to survive close to human habitation, giving a serious trouble for both the parties. Due to devastated eating of crop plants, humans always take precautions to avoid their entrance to the cultivation fields. This results killing by shot, trappings, and poisoning.
Both subsp. aurifrons and sinica are kept as pets by various indigenous people for economic purposes. They were heavily used by both Sri Lanka Army and LTTE for their shooting practices in the recent past, but now prohibited.
In an experiment, serum samples taken from toque macaque individuals at Polonnaruwa were examined for antibodies to Toxoplasma gondii by the modified agglutination test. There was no evidence of maternal transmission of antibodies or congenital toxoplasmosis. None of the infected macaques died within 1 year after sampling. Toxoplasma gondii infection was closely linked to human environments where domestic cats were common. Although infection with T. gondii has been noted in several species of Asian primates, this is the first report of T. gondii antibodies in toque macaques.
It's unclear if nonhuman primates also serve as a reservoir of human dengue viruses under certain conditions. According to a study by some biologists, a cross-sectional serologic survey was carried out to characterize the pattern of transmission of a recently identified dengue virus among toque macaques in Sri Lanka. The results indicated that an epizootic dengue virus was active among the macaques. A single epizootic had taken place between October 1986 and February 1987 during which 94% of the macaques within the 3 km2 study site were exposed to the virus. The epizootic was highly focal in nature because macaques living 5 km from the study population were not exposed to the virus. The transmission of dengue viruses among macaques in the wild may have important public health implications.
Macaca sinica is endemic only to the island of Sri Lanka. It is found in all areas of this country excluding the Jaffina Peninsula in northern Sri Lanka and is also not found in the Trincomalee area in northeastern Sri Lanka.
Biogeographic Regions: oriental (Native )
Other Geographic Terms: island endemic
Toque macaques are the smallest species of Macaca. They have a golden brown coat on their dorsal surface and white hair on their ventral surface. This white coat extends to the cheeks and around the ears. The have a small tuft of hair on the top of their head that resembles a hat. The amount of hair on the top of the head is geographically variable within their range. They have a long tail that is black dorsally and pale white ventrally. Toque macaques have muscular cheek pouches that are used for storage during foraging. These pockets are lined with mucous and the muscles serve to push the food back into their mouth. Individuals have thirty two teeth; their dental formula is 2/2, 1/1, 2/2, 3/3. There is sexual dimorphism in canine size, with males having larger canines. All of their molars are quadrucuspid. Their faces are hairless. Toque macaque males have a tan face while females have different shades of pink. Males are larger than females and complete their development later. Females have a head and body length of 400 mm while males are around 475 mm. Both males and females have long tails that are slightly longer than their head and body length. Their ears and lips are black. Toque macaques may be the smallest species of Macaca, but they have one of the largest tails compared to body size. They also have very large ears that are 9% of the head and body length. Their basal metabolic requirement is 150 kcal/kg daily. There are two described subspecies of M. sinica: Macaca sinica aurifrons, which lives in the lowland dry region in northern Sri Lanka, and Macaca sinica sinica, which lives in the wet evergreen forests in southern Sri Lanka. Macaca sinica sinica is slightly larger has darker, denser, dorsal hair.
Range mass: 2.5 to 6.12 kg.
Average mass: 4.2 kg.
Range length: 367 to 495 mm.
Average length: 448 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; sexes colored or patterned differently
Toque macaques live in a variety of biomes throughout Sri Lanka. They spend a large amount of time in trees and live in all types of forests. The type of trees and tree height varies with region. The most important resource is a source of drinking water. This accounts for the lack of any M. sinica in the northern penninsula and parts of southern Sri Lanka. As a result of occupying separate regions two sub species are recognized. The lowland species, Macaca sinica sinica, lives in northern Sri Lanka. This region has much smaller trees and only receives one meter of rainfall a year. The highland species, Macaca sinica aurifrons, lives in the evergreen forests of southwestern Sri Lanka. This region gets over three meters of rainfall a year.
Range elevation: 0 to 2100 m.
Average elevation: 1000 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest ; scrub forest
Other Habitat Features: agricultural ; riparian
Toque macaques spend much of their day foraging for food in trees and on the ground. They have special pouches in their cheeks that are used to store food during foraging. If they sense danger while foraging they will put their food in their mouth and flee to safety. Once safe they will eat the contents. The diet consists mostly of fruit. They also eat tree flowers, buds, and leaves. In their range there are 46 different types of trees, only 6 of which are not utilized for food. When available they will eat small invertebrates or vertebrates such as birds or lizards. Although these are not a main source of energy for M. sinica they represent an important source of protein and a considerable portion of time is spent searching for such prey. During the dry season water obtained from food is not enough to sustain toque macaques, so they must make daily trips to watering holes. Toque macaques also raid crop, such as rice, cocoa, and coconut.
Animal Foods: birds; mammals; reptiles; insects
Plant Foods: leaves; fruit; flowers; sap or other plant fluids
Other Foods: fungus
Primary Diet: herbivore (Frugivore ); omnivore
Toque macaques play many roles in their ecosystem. It is estimated that a troop will eat up to 1 percent of the annual fruit production of the forest they live in. Through their frugivory they also help to disperse seeds. They are predators of small lizards and birds, but these are not a staple of their diet. Toque macaques a commensal relationship with two species of monkeys, Hanuman langurs (Semnopithecus entellus) and purple-faced langurs (Trachypithecus vetulus), with which they co-occur. They are often observed foraging together. They do not compete for food resources as M. sinica primarily eats fruit and both Presbytis species eat leaves. They are hosts to a variety of parasites.
Ecosystem Impact: disperses seeds
Toque macaques spend most of their time in trees, which limits their exposure to potential predators. When on the ground they appear much more cautious then when they are in the trees. They avoid open spaces when possible. When they must be in the open, they stay in compact groups. When any member senses danger the whole group will flee to nearby trees. When frightened they sometimes freeze in place when in dense foliage. To avoid predation they sleep high in forks of trees that are far from the central trunk. Groups of M. sinica rarely sleep in the same tree over consecutive nights to avoid predation. They do fall prey to large, arboreal predators, including snakes, and possibly to large avian predators, although none are reported.
Toque macaques are diurnal primates that rely heavily on vision. They have excellent stereoscopic and color vision. Often they distinguish between food sources using their vision, instead of smell. As in other primates, Toque macaques have excellent control over their hands and feet. They have well developed thumb-index finger control. They use acoustic communication among individuals and groups. There has been 30 different vocalizations recorded. They use warning calls to alarm other group members of danger and other vocal communication during play. There is a clear dominance hierarchy in groups of M. sinica and the dominant male is easy to identify. He is generally well groomed and muscular. Grooming is a common social activity. During the breeding season females communicate that they are in estrous by secreting a pungent mucous from their cervix that males smell.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; tactile ; acoustic ; chemical
The lifespan of toque macaques in the wild is about the same as in captivity, up to 35 years. The expected lifespan in the wild is low due to high infant mortality rates. There is also significant mortality among adolescent males when they venture off to join a different troop. Once toque macaques have reached sexual maturity they will likely live to an old age.
Status: wild: 30 (high) years.
Status: captivity: 35 (high) years.
Status: wild: 4.5 to 4.8 years.
Status: captivity: 30 years.
During the late summer season every sexually mature female goes into estrus once a month for three months. Females in estrus secrete a pungent mucus from their vagina which serves as a signal of her fertility to potential mates. They are promiscuous and paternity of offspring is generally unknown. Once a pair are ready to mate they withdraw from their troop but are often followed by younger males who attempt to mate with the female after the first male. Although there is a well developed dominance hierarchy among troops of M. sinica, copulation frequency is not higher among the dominant males.
Mating System: polygynandrous (promiscuous)
Toque macaques have a three month breeding season in late summer. The exact month of breeding varies with location. In the breeding season females come into estrous once a month. Mounting is always initiated by a male. There is a six month gestation period. There are 0.69 young born per mature female yearly.
Breeding interval: Toque macaques breed once yearly.
Breeding season: Breeding season is generally between July and September.
Average number of offspring: 0.69.
Range gestation period: 5 to 6 months.
Range weaning age: 140 to 190 days.
Average weaning age: 170 days.
Average time to independence: 2 years.
Average age at sexual or reproductive maturity (female): 5 years.
Average age at sexual or reproductive maturity (male): 7 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
The majority of the parental investment is from females. Females invest significantly in gestation and lactation, during late pregnancy their energy requirements almost double. Females supervise groups of playing young together. Juveniles play in groups with other members that are the same age. Mothers provide protection to their young, but a mother will only protect its youngest child in the presence of danger. Young learn by watching older members of troops. Males provide little care to the young as there is no way to be sure of paternity.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); extended period of juvenile learning
Toque macaques are listed as endangered according to the IUCN Red List. Their population has been decreasing steadily and total population size has been cut in half over the last 40 years. This loss is due to habitat destruction and persecution of M. sinica by humans. Although they are protected internationally, they are not protected by Sri Lankan law. There are many parks and reserves in Sri Lanka where toque macaques occur.
US Federal List: threatened
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: endangered
There is significant persecution of toque macaques as they are considered crop pests. They are shot and poisoned as ways to keep them out of crops. They are also known zoonotic vectors of Trichuris, Ascaris, and certain strongyle worms.
Negative Impacts: injures humans (carries human disease); crop pest
Toque macaques are not economically important in Sri Lanka. They are widely viewed as pests because they raid crops and garbage dumps. They are sometimes sold as pets.
Positive Impacts: pet trade